DC Rainmaker has a pretty decent review, although it misses the elephants in the room, i.e. how it distinguishes different power outputs for different riders (i.e. it relies on population averages for mapping HR to power) and how it assesses changes in fitness/power (i.e. it doesn't) - which is kinda the whole point of power in the first place.

I was wondering how it actually judges power at all . I understand it isn't just for cycling. My heart rate zones were ( are ) never anywhere near what they were supposed to be corresponding to the power zones.Just interesting that powertap and more so Lim would do something like this.

Umm yeah. Heart rate doesn't tell you much about power, the effect is correlation, not causation. Even then it depends on fitness - you, I and a couch potato may have the same maximum heart rate but at 90% max HR exertion level our power levels would likely be very different, as is the duration we could hold it for. There seems to be no allowance for fitness. If they base it on Lactate Threshold HeartRate (LTHR) then it might be more value for money.

I've got one - it doesn't cause any glitches on the Garmin 800 outside of 255 Cadence when you are stopped. It reflects a little bit some of the power (eg w/kg) that I'd seen on a bike with a powertap, but otherwise I'm not going to vouch for its accuracy or otherwise.

In any case, the Powercal is like "Big Bertha" at Le Mans in 1971. Largely unproven - left of field and interesting. I prefer it to the Garmin premium heart-rate strap though.

The positive aspects of the Powercal seem to be missed here:1. At about one-tenth of the cost of a set of Powertap wheels and a smaller fraction of the cost of SRM cranks it is incredibly cheap.2. If the power figures are even a bit closer to actual power than heart rate numbers then you may get better results using this rather than heart rate alone. I haven't had it long enough to comment on that. It will be interesting to see if the power drops while my heart rate stays up when I'm fatigued. If so it's a useful tool.3. There is no installation required - just pair it with an ANT+ display and you're off.4. You can buy it once and use it on multiple bikes.

Worst case if you don't like the numbers it's a slightly expensive HR strap. My biggest gripe is that due to what appears to be non-compliance with the ANT+ standard for power meters (ie that cadence from a power meter is optional) the Edge 500 constantly displays a cadence of 255 when the Powercal is paired with it (despite a Garmin GSC10 speed/cadence unit also being paired and transmitting cadence information). Hopefully Garmin will fix this with a firmware upgrade at some point.

No doubt the power figures are a bit rubbery, but you have to admire the idea - HR monitors have been producing calory counts for years so it's clever in an obvious way to make a device that produces power based on heart rate. From what I've read the process isn't as trivial as suggested by some of these posts - I think it's more about how the heart rate changes than simply looking up a heart rate in a table.

I'm feeling a bit like this could be a winner for me, no good for sprint workouts but a lot easier to get the TSS and so forth, and honestly, I think I'm massively overtraining so something to force me to put the brakes on would be worth its weight in gold... or CycleOps plastic...

Mate... I've got a LOT of room for improvement... you should come for a ride around Rouse Hill Trek or Kangazilla one Saturday soon, and pretend you are a big man winning the coffee shop sprint cause I don't do that much at all

From looking at the analysis of HR/Pr from someone's software (power analysis plugin for SportsTracks), the calculated function to determine Pr from Hr changed for every ride, often significantly. If the strap is just working on HR and nothing else (ie., does it measure more inputs ala a proper ECG?) it's just a gimmick.

I think it must be getting some extra information in the HR impulse - there is a lot of physiological info available, and HR is only one of them. They could easily jig up the device to measure a nervous response with change of HR, and that would be more useful than just an HR measurement... I think the key seems to be that you can't rely on it for accurate intervals less than 30 seconds, but it's still better than HR alone. I'm satisfied with that... I'm just not able to do a TSS for a 3 hour ride because I am undisciplined and unaware of my RPE. I can either ride it easy, tempo or hard... more than happy to spend 40 bucks for a device to think for me.

Definitely seems to be the ducks guts if you are not going to use it for sprint intervals etc.

... and, seriously, even if you had a PM, you will find that TSS scores and the performance manager are a rubbery guideline rather than a solid guide. It's taken me a couple of years to work out what CTL I can build to for good performance, but the TSB is still pretty rubbery because some days I will feel weak when the model suggests I should be able to go our and hammer it.

yeah Twiz, it definitely seems to be as much art as science. I was reflecting this morning on the train about the best rides I've had, it's been a strong hit out on Saturday (usually the shorter flatter "slow" ride at 31 av), then a limping forward Monday morning, then brute force Monday evening, Tuesday... then resting until Saturday... commuting 20kms twice a day to work. Had some monster efforts midweek. Clearly TSB wasn't an issue these days lol

I'll just grab the thing, see how it goes. It's so much cheaper than any power solution (even Alex's cheap 400 dollar Powertaps are 4x the cost) that I don't think it can be discounted. I did some weights yesterday, first set of 30 only got the heart rate to 80-90bpm (after short warmup)... I'm skeptical on heart rate LOL because my legs definitely knew about it.

I still need a lot more time with this thing, but I'm coming around, slowly but surely. Firstly, the watts estimate is a complete joke. I wear the power meter on the trainer, and while the trainer says I'm holding around 400W, powercal claims more like 270-280W at the same time. But as long as that's repeatable, that's not terrible overall. I mean 400 is just a number, as is 36 or 280.

So I can manually calibrate this against the trainer and try to use that figure on the road, regardless of bike or wheel. To test this, I have a Calga TT under my belt now, and feel I rode almost as well as I could, so consistantly flat out for 40 minutes straight, with a little left in the tank afterwards. Powercal claims 235W average on this ride. My adjusted FTP on the trainer is currenly 240W, so it definitely seems I can take figures I work out at on the trainer, onto the road, which is excellent news.

My biggest problem with this was how it was jumping all over the place (which I know power meters do too), and seemed quite random sometimes. It's definitely slow at reacting. I'd be 30m up a steep hill, and it would say 130W, or I'd be stopped at lights and it would say I'm putting out 130W still. So for some peoples this lag may make it impossible to use. For my use, which is aimed at longer segment training and TT's right now, I can see the last 60 seconds average should be very useful, especially if I'm mainly maintaining similar power for 40 minutes during a race. For my next Calga race, I plan to just look down once a minute, make sure I'm not going too hard, and spend the next 59 seconds focusing on the race. So I'll have more to review after I give that a go.

Would I recommend? Hard to say yet. I still need more experience, and should probably really review it properly by using a power meter for a while and compare it with using real power figures. For now it seems useful as a cheap and easy power estimate.

That's weird... it seems to underestimate many people by 30% but they get happier once they are on the road as well... weird. I pulled the trigger and should have it in time for Father's Day (thanks boys hehehehe). Will be good to have the HR ability as well because my wife needs some cardio training BADLY.

And I'm testing it out now. I am thinking that 3s power is a bit excitable for my liking, but we'll see. You get power info while typing Resting heart rate staring at the screen is under 50bpm? Do a ride tomorrow, see how we go hey?

Edit: Hmmm HR got down to 42 and stayed around 45 while sitting in front of the TV

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